C-HARM HAB Model (California-Harmful Algae Risk Mapping)

Experimental Data - Use Cautiously

Pseudo-nitzschia Nowcast

The map image displays the probability that the abundance of toxin-producing species of the diatom Pseudo-nitzschia in coastal waters is at or above the “bloom” threshold of 10,000 cells per liter. A value of 0.7, for example, means there’s a 70% predicted probability of Pseudo-nitzschia blooms in that pixel.

Particulate Domoic Acid Nowcast

The map image displays the probability that the domoic acid concentration in the bulk phytoplankton pool is at or above 500 nanograms per liter (= 0.5 µ/L). A value of 0.7, for example, means there’s a 70% predicted probability of a toxic event, although there is always the possibility that concentrations lower than 500 ng/L will lead to toxins in shellfish or strandings of marine mammals and birds.

Cellular Domoic Acid Nowcast

The map image displays the probability that the domoic acid concentration per Pseudo-nitzschia (i.e. how toxic are the algal cells themselves) is at or above 10 picograms per cell (pg/cell).

To give a sense of the range, the highest cellular concentrations seen in the environment have not yet exceeded 200 pg/cell in the most toxic cells. A predicted probability value of 0.7, for example, means there’s a 70% probability that a 10 pg/cell level of toxicity is present in the phytoplankton, although there is always the possibility that concentrations lower than 10 will lead to toxins in shellfish or strandings of marine mammals and birds.

Cellular Domoic Acid (cDA) is a measure of how toxic the cells are in terms of per cell toxicity. Particlulate Domoic Acid could be thought of as a standing level of DA across all cells at the surface. Cellular DA appears to be a better representation of where food web effects are likely occurring, although this is not always the case. Research is being done to better understand this linkage.

Predictions of harmful algal bloom (HAB) conditions are created through a combination of 1) sophisticated circulation models that predict the ocean physics, 2) satellite remote-sensing data of the ocean “color” and chlorophyll patterns, and 3) statistical models for predicting bloom and toxin likelihoods. These predictions are generated daily to provide a forecast of where you might encounter a Pseudo-nitzschia bloom and/or domoic acid event in the next one to three days.

HAB Forecast Information

Blooms

Phytoplankton blooms are a recurrent, seasonal phenomenon along the California coast and are extremely important for supporting our diverse coastal food webs and biomass-rich fisheries.

Pseudo-nitzschia and Domoic Acid

The diatom Pseudo-nitzschia is a natural part of this algal community and helps feed an abundance of zooplankton and fish. Unfortunately, for reasons still not well understood, several species in this diatom group will produce a deadly neurotoxin called domoic acid. The sea lions that strand with signs of illness, lethargy, confusion, or seizures during spring and summer months along the CA coast are often suffering from domoic acid toxicosis acquired from feeding on toxic fish. Production of this domoic acid is not entirely linked to how many cells of Pseudo-nitzschia are present, which means that even when there is a bloom, we may not be able to directly calculate how much domoic acid is present in the water.

Predictions of Harmful Blooms

Certain environmental factors have been shown to be associated with blooms and with domoic acid production by Pseudo-nitzschia. Statistical analysis allows us to create models that will produce a likelihood of finding high numbers of Pseudo-nitzschia cells in the water, much like a weather forecast that provides the probability of precipitation on a given day. Models also tell us the likelihood that we might encounter what we consider to be high concentrations of domoic acid.

Product Information

Nowcasts are generated by merging data from a 3-km regional ocean model system (ROMS) that simulates ocean temperature and salinity for California coastal waters with 1-km satellite estimates of chlorophyll and remote-sensing reflectance (ocean color) from NASA sensors. The ROMS model domain does not cover the interior of San Francisco Bay. An important step is the statistical “filling” of gaps in the satellite data that are mostly due to cloud cover using a program called Dynamic Interpolation using Empirical Orthogonal Functions (DINEOF). Once the “filled” satellite and ROMS data are merged, the statistical models for Pseudo-nitzschia and domoic acid are computed at each pixel using those merged data in order to create maps with color scales representative of the likelihood (or probability) of a bloom or toxic event.

Forecasts of Pseudo-nitzschia and domoic acid are produced in a similar manner to the nowcasts in terms of merging ROMS and NASA satellite data, however, in order to make 1-3 day projections, we run DINEOF on ROMS-projected temperature, salinity, and ocean currents along with satellite ocean color data in order to project the biological variables (i.e. chlorophyll) forward in time. We then compute future bloom likelihoods from these projections. .

Map images provide these probabilities for Pseudo-nitzschia “blooms” and for domoic acid “events.” The domoic acid predictions are divided into “particulate,” meaning how much total domoic acid is present, and “cellular,” referring to the amount of domoic acid being produced by an individual cell (i.e. how toxic are those cells). The predictions are updated daily and soon will include 1-3 day forecasts.

Project Contacts

HAB Forecast Tutorial

The images above provide probabilities for Pseudo-nitzschia “blooms” and for domoic acid “events.” The domoic acid predictions are divided into “particulate,” meaning how much total domoic acid is present, and “cellular,” referring to the amount of domoic acid being produced by an individual cell (i.e. how toxic are those cells). The predictions are updated daily and soon will include 1-3 day forecasts.

Pseudo-nitzschia Bloom Prediction Images

Map images display the probability that the abundance of toxin-producing species of the diatom Pseudo-nitzschia in coastal waters is at or above the “bloom” threshold of 10,000 cells per liter. A value of 0.7, for example, means there’s a 70% predicted probability of Pseudo-nitzschia blooms in that pixel.

Domoic Acid Event Prediction (for particulate DA)

Map images display the probability that the domoic acid concentration in the bulk phytoplankton pool is at or above 500 nanograms per liter (= 0.5 micrograms per L). A value of 0.7, for example, means there’s a 70% predicted probability of a toxic event, although there is always the possibility that concentrations lower than 500 ng/L will lead to toxins in shellfish or strandings of marine mammals and birds.

Domoic Acid Toxicity Prediction (for cellular DA)

Map images display the probability that the domoic acid concentration per Pseudo-nitzschia (i.e. how toxic are the algal cells themselves) is at or above 10 picograms per liter (pg/L). To give a sense of the range, the highest cellular concentrations seen in the environment have not yet exceeded 200 pg/L in the most toxic cells. A predicted probability value of 0.7, for example, means there’s a 70% probability that a 10 pg/L level of toxicity is present in the phytoplankton, although there is always the possibility that concentrations lower than 10 will lead to toxins in shellfish or strandings of marine mammals and birds.

We are soliciting the community to consult our product and provide feedback, particularly if HAB predictions have the potential to help in decision-making activities. The quick survey will help guide improvements and allow us to report to NASA what you, as important end-users, think about our product.